Docs: equality: mistake in "Types of equality" table

[mb64]

Hi all! I'd submit a PR but I can't find the source for the docs. On the page equality, the table says that equal-always is like OCaml's (=).

However, OCaml's (=) implements equal-now:

$ ocaml
# ref 3 = ref 3;;
- : bool = true
# ref 3 == ref 3;;
- : bool = false

I would recommend Haskell's == as an example of equal-always (I think SML's (=) too but I'm not an SML programmer):

ghci> x <- newIORef 3
ghci> y <- newIORef 3
ghci> x == y
False

A minor thing, but I have had a tricky bug in the past from using OCaml's (=) and thinking it was like Haskell's (==), so when I saw the table I thought I'd report it.

[sorawee]

Here's the file you are looking for: https://github.com/brownplt/pyret-docs/blob/horizon/src/lang/equality.scrbl#L281